Gases such as ethylene, hydrogen peroxide (H 2 O 2 ), nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H 2 S) have been recognized as vital signaling molecules in plants and animals. Of these gasotransmitters, NO and H 2 S have recently gained momentum mainly because of their involvement in numerous cellular processes. It is therefore important to study their various attributes including their biosynthetic and signaling pathways. The present review provides an insight into various routes for the biosynthesis of NO and H 2 S as well as their signaling role in plant cells under different conditions, more particularly under heavy metal stress. Their beneficial roles in the plant's protection against abiotic and biotic stresses as well as their adverse effects have been addressed. This review describes how H 2 S and NO, being very small‐sized molecules, can quickly pass through the cell membranes and trigger a multitude of responses to various factors, notably to various stress conditions such as drought, heat, osmotic, heavy metal and multiple biotic stresses. The versatile interactions between H 2 S and NO involved in the different molecular pathways have been discussed. In addition to the signaling role of H 2 S and NO, their direct role in posttranslational modifications is also considered. The information provided here will be helpful to better understand the multifaceted roles of H 2 S and NO in plants, particularly under stress conditions.

Nitric oxide and hydrogen sulfide crosstalk during heavy metal stress in plants